The invention provides a Chinese medicinal composition for preventing and treating obesity. The composition is an oral preparation which is prepared from medlar, lotus leaf, south dodder seed, tuber onion seed and cassia seed serving as raw material medicaments, and auxiliary materials by the conventional pharmaceutical process. The composition has the effects of removing dampness and relaxing the bowels, burning fat and expelling toxin, and warming yang and reinforcing the kidney so as to fulfill the aims of losing weight and slimming. Clinical data researches prove that the composition has obvious effect of preventing and controlling multiple kinds of obesity; meanwhile, the raw materials can be used as medicaments and foods, so the composition has good health-care effect on human bodies.